Hot water heating systems provide a clean and comfortable source of heat in a building, dwelling or other structure. Hot water heating systems have the added benefit of keeping the air moist. Typically, a hot water heating system includes a heat source powered by either electricity or burning of a high grade fuel (e.g., a fossil fuel), a water circulation system, a water temperature sensing device for controlling the rate of combustion in the heat source, and a thermostat for controlling the rate of circulation of water throughout the system. The water circulation system is commonly configured to pass cool water near the heat source to heat the water, conduct or pass the heated water to remote radiators, and returning the cooler water to the heat source for reheating. Typical forced air heating systems pass cool air near a heat source and into the heat duct work system throughout the house. Commonly, the heat source is a furnace which burns a high grade fuel such as natural gas, oil, coal or any other fossil fuel.
High grade fuels are typically utilized in heating systems (e.g., hot water and hot air systems) due to their steady, easily adjustable rate of combustion. However, such fuels are also characterized by their relatively high cost, which is steadily increasing, especially with respect to home heating oil and even natural gas. Further, such fuels negatively impact the environment. For example, burning fossil fuels releases relatively large quantities of sulphur dioxide, nitrogen oxides and carbon dioxide which can contribute to acid rain and global warming. Further, fossil fuels are non-renewable resources with a limited lifespan. More efficient hot water heating systems have therefore become desirable to reduce heating costs, conserve fossil fuels, and at least reduce the negative impacts to the environment as compared to conventional fossil-fuel burning heating systems.
A widely accepted and used water heater for residential hot water production and storage, rather than for heating purposes, is the electric resistance water heater and storage tank. Water heaters typically include a tank defining a chamber for retention of water. A water inlet pipe that is provided with a first connection for interconnection with a cold water supply line that conveys fresh relatively cold water into the chamber. Within the tank there are electric resistance elements that heat the water in the tank. In current embodiments, there are at least two electric resistance elements. A first electric resistance element positioned near the bottom of the tank and a second electric resistance element positioned near the top of the tank. There are also two sensors positioned on the exterior of the tank that measure the temperature of the tank near the top and bottom of the tank in proximity to the location of the electric resistance elements. When the temperature sensed by such sensors drops below a certain temperature level, these sensors close the contacts associated with the corresponding electric resistance elements causing the electric resistance elements to energize.
When water is supplied to the tank, it is supplied through a dip tube that pushes the cold water to the bottom of the tank and thereby pushes the hot water out of the top through the outlet pipe where water is the hottest. One of the problems with this configuration is that the sensor near the top of the tank can't detect that hot water is exiting and cold water is entering the tank near the bottom. The lower sensor detects that cold water is entering the tank when it detects a temperature drop at the thermostat, which is the primary purpose for having two sensors. When the lower sensor detects a temperature drop below a certain level, it closes the contact and energizes the lower electric resistance element until the temperature reaches a specified level. But, each time the lower electric resistance element heats the water; the heated water is buoyant and goes up to the top of the tank. For example, if the tank is holds 50 gallons of water, and three gallons of water flow into the tank, it may cause the lower electric resistance element to be energized for a few minutes in order to recover the temperature. If a few minutes later, there is a draw of another three gallons of water, the lower electric resistance element is energized again for another few minutes in order to recover the temperature. This causes the heated water to rise to the top creating a problem called stacking.
Under sequential small draws of water, the lower electric resistance element is energized each time and runs until the lower sensor is satisfied that the lower part of the tank is sufficiently warm. When this is occurring, the top part of the tank continues to get a little bit hotter each time which causes over heating of water in the top of the tank, which can potentially lead to undesirably hot water being drawn from the tank. There is therefore a need for a hot water heater configuration that solves the problem associated with stacking resulting from small sequential water draws made on current water heaters. Further, such electric resistance hot water heaters and storage tanks are thereby unable to produce the volume of hot water needed for hot water heating systems, and are less efficient that typical hot water heating systems as describe above.
The present disclosure provides hot water heating systems that overcome the above noted drawbacks and problems of existing hot water heating systems and water heaters.